Plant Populations

Relative cotton yield versus plants per
foot of row from Missouri and South
Carolina

Cotton Skippy Stands. Field tests are being conducted in Missouri and South Carolina to evaluate uniform and random plant stand reductions in cotton rows. Treatments were applied to simulate 50 to 90% plant reductions by hail storm at early square. Uniform reduction were made by blending conventional (non-glyphosate resistant) and glyphosate resistant seeds and spraying with glyphosate. Random stand reductions were acheived by hand thinning based on a random number generator. For comparisons, even stands were planted with normal and low seeding rates. Results from 2007 will be presented at the Beltwide Cotton Conference in Nashville, TN.

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Cotton Planting Date and Plant Population. Cotton producers in the Mississippi Delta plant in early spring, but wet, cold weather often develops which may reduce plant population. Producers must occasionally decide if replanting is necessary. The objective of these studies was to determine planting date and plant population effects on cotton yield, lint quality, and crop maturity. Three separate field experiments were conducted during 2001-2005.Yield for late-April planted cotton at 6,900 plants/acre was significantly greater than or equal to yields for mid-May planted cotton at all plant populations. Lint yields and percent lint were significantly greater for early than late plantings three of five years, and micronaire was significantly greater for early than late plantings each year. In all experiments, crop maturity was delayed for late planting dates and low plant populations. A decision support aid program was written in Excel based on the research. Producers in the Mississippi Delta should not replant cotton after mid-May if large skips are not present and the plant population from a late-April planting is 7,000 or more plants per acre. READ MORE

Grain Sorghum. Adverse weather and soil conditions sometimes prevent grain sorghum farmers from achieving an evenly spaced, optimum plant population in their fields. Farmers must decide whether to replant or manage a grain sorghum crop with reduced yield potential. Research showed that grain sorghum was able to partially compensate for stands below 60,000 plants acre-1 by producing larger grain heads. In evenly spaced grain sorghum, 100 to 150 lb N/acre produced the highest grain yields in both high and low population conditions. Grain sorghum on 30-inch row spacing with frequent 6 to 9-foot skips had significantly reduced yields as compared to grain sorghum with optimum plant densities. No significant interaction in grain sorghum yield response to nitrogen was found between rows with plant skips and rows without plant skips. Crop Management paper.

Effect of skip number and length on grain sorghum yield averaged across N rates and years at Portageville, Missouri in 2002 and 2003.